docs: def _get_stddevs(self, C, stddev_types, num_sites, mag):
          """
          Returns standard deviation as defined in equation 23, page 2291
          (Tavakoli and Pezeshk, 2005)
          """
          stddevs = []
          sigma = (C['c14'] + C['c15'] * mag) if mag < 7.2 else C['c16']
          vals = sigma * np.ones((num_sites))
          for _ in stddev_types:
              stddevs.append(vals)
          return stddevs